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Naftali Murgor
Naftali Murgor

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Introduction to E2015 Set Objects

#javascript #webdev #node #html

Introduction

Set objects are constructed using new Set().

Set object

A set is a “set of " unique values. Say you have a simple game and need to track the position of mouse clicks. You’d store every position in a set object. Duplicate values are discarded when an attempt to add the set object is made.

Sample code showing a simple Set object usage:

function main() { const gameScreen = document.getElementById('game-screen') gameScreen.addEventListener('click' updateAction) const cursorPositions = new Set() function updateAction(event) { let position = {x: e.clientX, y: e.clientY} cursorPositions.add(position) // any duplicate values are discarded, which is ideal in this case } // use unique cursorPositions below } while(true) { main() }
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Duplicate values are discarded when added to a set. This is useful for capturing and storing unique values where duplicate values are not needed.

const letters = new Set() letters.add('A') letters.add('B') letters.add('A') // duplicate entry is ignored console.log(letters) // Set {2} {'A', 'B'}
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Summary

  1. The set object provides a way of storing data where duplicate values are not required.

Note: Most languages including JavaScript offer a lot of language features but it’s not a good approach to try learning all these language features at a go. However, knowing they exist is enough as it helps one know where to look when the need arises.

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